Omnicom has primarily handled work on the Pepsi brand in the past. In recent years, however, the brand has not restricted itself to Omnicom agencies and has worked with agencies outside the network, including Mekanism. In 2008, PepsiCo shifted lead creative duties from BBDO to TBWA\Chiat\Day for the brand after over 50 year with the former shop. BBDO started working with the brand again in 2015.
Read more at Agency Spy: http://www.adweek.com/agencyspy/pepsi-calls-on-omnicom-agencies-for-closed-u-s-brand-review/134133